1. Field of the Invention
The present invention relates to a lighting device having an energy conversion module, and more particularly, to a lighting device equipped with an energy conversion module that receives light energy from a variety of commonly used lamps, such as fluorescent lamps, and converts the light energy into electrical energy.
2. Description of the Related Art
The use of lighting devices is universally prevalent. Along with the progression of time, the technology of lamps also evolves, from the use of incandescent light bulbs to fluorescent tubes and to white light-emitting diodes (LEDs) nowadays. The evolution is not only about new lamp styles, but also about improvements in illumination efficiency. Fluorescent lamps are one type of lighting devices commonly used; usually, there is a reflection layer coated on the metal support, e.g., the shade, of the fluorescent tube for enhancing the illumination effect (illuminance) and improving energy efficiency. Conventional lighting devices are used typically for illumination only. How to make further use of light sources to enhance energy utilization efficiency is a meaningful task.
A photovoltaic cell absorbs light energy to generate electricity. For instance, silicon-based solar cells absorb sunlight to produce electricity. But such solar cells are not efficient in absorbing light energy generated by indoor lighting devices. By contrast, dye-sensitized solar cells can absorb both indoor and outdoor light, including sunlight and light from lighting devices, and exhibit better energy conversion efficiency. A dye-sensitized solar cell (DSSC) converts light energy into electrical energy by a photoelectrochemical energy conversion mechanism. Its operation principle is different from that of a silicon crystal solar cell or a thin film solar cell which uses silicon as material. A DSSC generally consists of two pieces of transparent conducting oxide (TCO) glasses: one TCO glass is an electrode on which semiconductor oxide material such as nanocrystalline titanium oxide (TiO2) layer is deposited; the other is a counterelectrode which has platinum thin film on it. In between two electrodes, there are electrolyte and dye molecules adsorbed in TiO2 layer. After the two electrodes are properly packaged and sealed, a DSSC is completed. When sun light irradiates a DSSC, the dye molecules release electrons that pass through the TiO2 layer and TCO layer to an outer circuit for generating electricity. The electrons then go to the counterelectrode, where they undergo the electrocatalytic activity of the platinum and redox reaction of the electrolyte, and return to the dye molecules to complete the cycle. A DSSC absorbs solar energy within the range of visible light spectrum. In addition to absorbing solar radiation in an outdoor environment to generate electricity, a DSSC can also generate electricity at lower light intensity either in an indoor environment or under lighting devices; therefore it can be used in both outdoor and indoor environments. Besides, a DSSC uses more common materials, such as conducting glass, titanium oxide, platinum, electrolyte and dye. Also, manufacturing a DSSC does not require expensive equipments such as PECVD equipment, but requires only inexpensive equipments like screen printers, sintering ovens, etc. Therefore, compared with silicon-based solar cells, DSSCs are advantageous in reducing manufacturing cost. A DSSC can have various colors based on the dyes it uses, and it can also be made on flexible substrates. The DSSC is a new-generation solar cell of multiple applications. In sum, using such dye-sensitized solar cell to absorb light energy and convert it into electrical energy for use in other devices can enhance energy utilization efficiency and facilitate uses of products.